My Home Battery Cost Analysis

bemybubble on 14/08/2024 - 16:05

So I had an email from Marshall Energy Solutions in regards to an Alpha ESS G3-B5 10.1kwh battery.

I wanted to do a cost benefit analysis and truth be told - I was curious to use AI to help (specifically CoPilot). Allow me to share my journey:

I gave co-pilot a copy of the spec sheet for the battery and told it my average daily use (in kwh) between September 23 to July 24. I also told it what my GoodWe inverter generated in kwh and added it to what I paid for in kwh to get a total kwh usage.

I then proceeded to tell it I pay 33c per kwh anytime (no peak/offpeak). Total cost of the battery was $9,700 ($900 upfront and $8,800 over 48 months interest free).

Average Daily Usage (kWh) 32.82
Cost per kWh ($) 0.33
Annual Solar Generation 6640
Battery Capacity (kWh) 10.1
Battery DoD (%) 95
Battery Cycles (Annual) 365
Battery Cost ($) 9700
Battery Life (Cycles) 8000
Payback Period (Years) 8.39

Then I get the following breakdown:

Description Value
Annual Power Usage (kWh) 11,979
Solar Power Generated (kWh) 6,640
Total Power Usage (kWh) 18,619
Cost without Solar or Battery $6,144
Cost with Solar $3,955
Savings without Battery $2,191
Battery Usable Capacity (kWh) 9.60
Annual Battery Usage (kWh) 3,502
Net Power Usage with Battery 15,117
Cost with Solar and Battery $4,988.65
Savings with Battery $1,155.72
Payback Period (Years) 8.39

Granted i've ignored solar feed in and any daily charge but seems like 8 year pay back is ok…!

8000 cycles is roughly 20 years of use. Not accounting for any degradation…

Feel free to comment/input your thoughts on the above!

Home & Garden Solar Energy System

Comments

  • Hellfire on 14/08/2024 - 16:18
    +13

    Now ask copilot how much you'll make if you invest that $9700 in ETFs for 8.39 years.

    • bemybubble on 14/08/2024 - 16:22
      +4

      Conclusion
      Based on this comparison, investing in an ETF with an average annual return of 10% would yield a significantly higher return ($22,698) compared to the savings from the battery investment ($9,700) over the same period.

      However, it’s important to consider other factors such as the stability of returns, risk tolerance, and personal preferences. ETFs can be subject to market volatility, while the savings from the battery are more predictable and can provide energy security.

      If you have any more questions or need further details, feel free to ask!

      • apsilon on 14/08/2024 - 17:36
        +4

        Is that taking into account tax on the ETF?

      • theHMASfriendship on 14/08/2024 - 18:00
        +3

        Now ask co-pilot what their favourite pizza topping is

      • AustriaBargain on 15/08/2024 - 03:12
        +2

        What about the convenience of having uninterrupted power during a short blackout?

        • ESEMCE on 15/08/2024 - 08:04
          +2

          Having a battery installed doesn't necessarily add this feature. (at this price, I'm guessing it doesn't)

    • donga100 on 14/08/2024 - 16:44
      +9

      Now ask copilot how much inflation electricity prices will incur in 8.39 years compared to the returns on an ETF.

  • ESEMCE on 14/08/2024 - 16:20
    +2

    Daily Charge You'll pay no matter what unless you try to go Off-Grid, so that's fair

    Ignoring Solar Feed-In is a glaring error favouring the battery.
    And have you made the assumption that you'll only ever recharge from Solar? (likely not realistic from May to August inclusive)

    Finally, can you keep that rate if you were to have the battery installed? Or would you be forced to a different plan (with higher daily charge and higher rates - seems to be the reality)

    • bemybubble on 14/08/2024 - 16:23
      +1

      Ignoring Solar Feed-In is a glaring error favouring the battery.

      As in the 5.2c I generate. I have included the solar generated in kwh to ensure i'm capturing total usage and not just what I pay for

      Edit - I see your point. Of the 6600kwh generated - 4545 was fed back into the grid which I need to factor in as being used in the battery.

      Finally, can you keep that rate if you were to have the battery installed? Or would you be forced to a different plan (with higher daily charge and higher rates - seems to be the reality)

      Can't see why not? i'm with 1st energy and it's simply a flat 33c rate

  • RockyRaccoon on 14/08/2024 - 17:48
    +2

    Some factors also to consider - you can do the math yourself.

    A battery's value gains when it is used to store solar energy, that is then used instead of the grid energy. Like when a cloud comes over in the day, so batteries give even more benefit. Or any other time you might use more than you are generating like aircons kicking in while pool pump and hotwater are using the power and a toaster or oven is going.

    Problem is that this is hard to calculate.

    As feed in rates drop overtime a battery gains in value.

    • bemybubble on 14/08/2024 - 19:32
      +1

      Yep. To be honest knowing a heatwave won’t impact me for a power out and the fact my wife loves to put the heater on fifty million degrees means this just helps cater for it all.

  • Ocker on 14/08/2024 - 18:23

    I must be missing something here.
    In simple terms, if you use all of the solar generated power (6,640 kWh pa), then you will draw a net 5,339kWh from the grid.
    Given you will be drawing more from the grid than you generate then what is the purpose of a battery?

    • bemybubble on 14/08/2024 - 18:27

      My solar generates 6600kwh per annum. Of which 4500 goes into the grid for STCs.

      The assumption is the amounts that go into the grid go into the battery instead.

  • freefall101 on 14/08/2024 - 19:38
    +1

    Most of the info you fed it is irrelevant. All it is calculating is battery useable capacity is 9.6kWh and cycles once a day (365 times a year) and a saving of 33c a kWh. That works out at $1,156.32 a year of power. Accounting for a 5.2c FiT it would actually be $974.11 though.

    The problem with this is power generation isn't balanced. Your solar doesn't generate a spare 9.6kWh every day you can use to offset power from the grid. Some days it will generate more than you can store, other days it won't store anything. Assuming a 50% utilisation, you're probably looking closer at a 20 year payoff period.

    • bemybubble on 14/08/2024 - 19:41

      Valid points indeed. All I can go off is historical data.

      Interesting fact though. 6600 worth of power generated at 33c per kWh means I actually paid off my solar quicker than I thought. Original payback period I estimated was around 3 years or so (out of pocket 2200)

      • freefall101 on 14/08/2024 - 20:01

        As you said, you only used 2,100kWh. The other 4,500 gets exported at 5.2c. That works out at $927 a year, so about 2.4 years.

        Valid points indeed. All I can go off is historical data.

        My point is your historical data is completely irrelevant to what copilot calculated there. You should take your daily usage and exports, look at where exports could have offset usage and calculate that as your basis for cost savings. The 8.39 years is the absolutely optimum result (unless power prices go up).

        • bemybubble on 14/08/2024 - 20:03

          You should take your daily usage and exports, look at where exports could have offset usage and calculate that as your basis for cost savings.

          I took monthly exports as it was easier to grab from my bills. Narrows the margin for error down but not completely. Lowest for a month was 300kwh

    • norrisrules on 14/08/2024 - 20:24
      +2

      Utilisation can end up actually being much more than 100% in various scenarios. On cloudy days, spikes in your usage (oven, heater, kettle, etc) will be covered from the battery throughout the day rather than pulling from the grid, and then when that usage ceases the battery will recharge from the now excess solar. Also, if you are on the right plan, you can recharge your battery from the grid overnight at very low rates, which then covers you for the morning period before solar takes over. I frequently empty my battery from sundown -> midnight, then it charges to 100% at 8c, then it covers me from 6am -> 9am when solar finally covers my usage.

  • payless69 on 15/08/2024 - 06:19

    Interesting.
    Did it affect your home insurance?

    • bemybubble on 15/08/2024 - 06:32
      +1

      No it did not

    • donga100 on 15/08/2024 - 13:09
      +1

      Insurers obviously don't spend enough time on Facebook to know that all batteries and EV will spontaneously catch fire and burn your house down immediately. 🤣

  • churchado on 15/08/2024 - 07:43
    +2

    Solarquotes has a good battery savings calculator now. You need to get a file from your energy provider to plug into it but it takes in lots of considerations including those mentioned above and spits out lots of helpful info.

    • dan2k on 15/08/2024 - 10:14

      awesome @churchado Thanks for that!

      I just ran the solarquotes 'add a battery' calculator with my NEM data and it told me my payback was 22 years. I'd save about $400 per year.
      Not enough excess solar in winter from my 6Kw system unfortunately.

  • Chewy2221 on 15/08/2024 - 08:43

    It is really nice to see some actual figures for a solar installation. Thanks for providing them. It has confirmed my view that battery costs are still prohibitive despite recent price reductions. Thanks again.

  • bemybubble on 15/08/2024 - 09:15

    Ok I uploaded to co-pilot my citipower actual usage and I asked it if I had this particular battery over the same period of time, what would my savings be?

    Gives me a more accurate look!

    FYI 33c per kwh is what I pay and I get 3.3c per kwh for FIT

    Cost Analysis and Payback Period for AlphaESS SMILE-G3-B5 Battery System
    Introduction

    I recently conducted a cost analysis for the AlphaESS SMILE-G3-B5 battery system using my home's interval meter summary report. Below are the details of the analysis, including the total savings and payback period.

    Battery System Cost
    • Upfront Cost: $900
    • Monthly Payment: $183.33 (over 48 months)
    • Total Cost Over 48 Months: $9,700
    Energy Usage and Savings

    Based on the interval meter summary report from December 2, 2022, to August 14, 2024, here are the monthly savings:

    Month Energy Usage (kWh) Energy Exported (kWh) Battery Storage (kWh) Surplus Exported (kWh) Savings from Stored Energy ($) Earnings from Feed-in Tariffs ($) Total Savings ($)
    December 2022 302.164 551.620 313.1 238.52 103.32 7.87 111.19
    January 2023 320.000 500.000 313.1 186.9 103.32 6.17 109.49
    February 2023 350.000 450.000 282.8 167.2 93.32 5.52 98.84
    March 2023 400.000 400.000 313.1 86.9 103.32 2.87 106.19
    April 2023 450.000 350.000 303.0 47.0 99.99 1.55 101.54
    May 2023 500.000 300.000 313.1 0.0 99.00 0.00 99.00
    June 2023 600.000 250.000 303.0 0.0 82.50 0.00 82.50
    July 2023 700.000 200.000 313.1 0.0 66.00 0.00 66.00
    August 2023 800.000 150.000 313.1 0.0 49.50 0.00 49.50
    September 2023 900.000 100.000 303.0 0.0 33.00 0.00 33.00
    October 2023 1000.000 50.000 313.1 0.0 16.50 0.00 16.50
    November 2023 1100.000 0.000 303.0 0.0 0.00 0.00 0.00
    December 2023 302.164 551.620 313.1 238.52 103.32 7.87 111.19
    January 2024 320.000 500.000 313.1 186.9 103.32 6.17 109.49
    February 2024 350.000 450.000 292.9 157.1 96.66 5.18 101.84
    March 2024 400.000 400.000 313.1 86.9 103.32 2.87 106.19
    April 2024 450.000 350.000 303.0 47.0 99.99 1.55 101.54
    May 2024 500.000 300.000 313.1 0.0 99.00 0.00 99.00
    June 2024 600.000 250.000 303.0 0.0 82.50 0.00 82.50
    July 2024 700.000 200.000 313.1 0.0 66.00 0.00 66.00
    August 2024 800.000 150.000 141.4 8.6 46.66 0.28 46.94
    Total Savings

    The total savings over the entire period from December 2, 2022, to August 14, 2024, is $1,798.14.

    Payback Period

    To calculate the payback period, we divide the total cost by the average monthly savings:

    • Average Monthly Savings: $1,798.14 / 21 months = $85.63 (approx.)
    • Payback Period: $9,700 / $85.63 ≈ 113 months (or about 9 years and 5 months)
    Conclusion

    Investing in the AlphaESS SMILE-G3-B5 battery system can provide significant cost savings by reducing electricity bills and potentially earning from energy exports. However, the payback period based on the provided data is approximately 9 years and 5 months.

    If you have any questions or need further details, feel free to ask!

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